The present invention relates generally a vessel and, more particularly, to a seal for a vessel. The vessel can be incorporated, for example, into a refrigeration system.
A refrigeration system comprises a compressor which conveys compressed refrigerant in a gas state to a condenser where it is cooled into a liquid state and passed to an evaporator. In the evaporator, the now-liquid refrigerant evaporates into a gas thereby absorbing heat energy and cooling an associated area. Thereafter, the now-gas refrigerant flows back to the compressor to repeat the cycle. A regulator supplies oil to the crankcase of the compressor to lubricate its moving parts and to enhance sealing of its piston for efficient compressing. An accumulator/separator can be provided to separate the oil (which becomes atomized and mixed with the refrigerant in the compressor) from the vapor so that only refrigerant is conveyed to the condenser input. A muffler can also be provided either upstream or downstream of the compressor to reduce noise levels.
A regulator, an accumulator, and a muffler each typically comprise a vessel having inlet/outlet fittings for connection to the appropriate system line. For example, the regulator can have an inlet fitting in its top end wall for connection to a supply line of an oil reservoir. The accumulator can have an inlet fitting in its top end wall for connection to the compressor discharge line, an outlet fitting in its top end wall for connection to the condenser input line, and an outlet fitting in its bottom end wall for connection to a drain line to the oil reservoir. If the muffler is a suction muffler (i.e., upstream of the compressor), it can have an inlet fitting on its top wall for connection to the evaporator output line and an outlet fitting on its top wall for connection to the compressor suction line. If the muffler is a discharge muffler (i.e., downstream of the compressor), it can have an inlet fitting in its top wall for connection to the compressor discharge line and an outlet fitting in its bottom wall for connection to the condenser input line. In any event, the interface of the inlet/outlet fittings in the top or bottom walls create joints in the vessel""s construction.
Regulators, accumulators, and mufflers are typically mounted on or near the compressor whereby compressor-generated vibration is transmitted thereto. This vibration can stress any susceptible joints in the vessel construction and the stress level can be sufficient to fatigue and damage the individual components.
In some applications, it may be desirable to attach a device such as a pressure relief valve or a refrigerant line onto the vessel using a threaded fitting. Accordingly, the vessel can be provided with a compatible inlet fitting to receive the device. The inlet fitting should have a sealing surface and a threaded protrusion to mate with the device. However, known techniques for forming such an inlet fitting have proved,to be problematic.
One technique for forming the fitting includes extruding a metal blank to form the inlet fitting. The process of extrusion typically includes piercing a hole in the blank and then flanging the metal surrounding the hole to produce a protrusion of metal which extends longitudinally from the parent metal of the blank. The length of the protrusion is limited by the strain capacity of the metal, which, if exceeded, will cause the edge of the protrusion to fracture or split. In addition, extrusion of the metal thins the thickness of the protrusion wall, especially at the end of the protrusion and where the protrusion meets the parent metal. Therefore, the resultant protrusion will have a tapered wall thickness and will have a relatively large radius where the protrusion meets the parent metal. These characteristics are not well suited to receiving a threaded fitting.
According, there is a need in the art for a vessel having an inlet fitting adapted to receive a threaded device, such as a pressure relief valve or a refrigerant line. There is also a need in the art for techniques for forming such an inlet fitting.
The present invention provides a vessel comprising a cylindrical wall and at least one end wall. The cylindrical wall comprises an edge portion turned radially inward to a diameter less than the end wall""s outer diameter, a shoulder portion having an inner diameter less than the end wall""s outer diameter, and a capture portion having an inner diameter only slightly greater than the end wall""s outer diameter. The end wall is interference-fit in the capture portion with the shoulder portion forming a positive stop therefor.
The end wall can be a top end wall, a bottom end wall, or both the top end wall and the bottom end wall can be attached to the cylindrical wall in this interference-fit manner. The walls can be made of simple shapes, for example, the cylindrical wall can have a generally constant circular crosssectional shape, and the shoulder and edge portions and the end walls can have a circular shape. A seam can be formed (e.g., by welding, brazing, or soldering) between the outer diameter of the end wall and the cylindrical wall if necessary or desired.
The end wall can have an inlet/outlet fitting extending through an opening therein and secured thereto. For example, an oil regulator can have an inlet fitting for connection to a supply line from an oil reservoir, an accumulator can have an inlet fitting for connection to a compressor discharge line and/or an outlet fitting for connection to an evaporator input line, and a muffler can have an outlet fitting for connection to the compressor suction line. In any event, it has been found that with the vessel design of the present invention, the inlet/outlet interface joints formed by these fittings are subjected to less compressor-generated vibration.
The vessel of the present invention can be easily fabricated by forming a shoulder portion in the cylindrical wall, placing the end wall on the positive stop formed by the shoulder portion, and turning the edge portion over the end wall. The end wall can be welded, brazed, or soldered to the cylindrical wall if an inter-wall seam is necessary or desired.
These and other features of the invention are fully described herein and particularly pointed out in the claims. The following description and drawings set forth in detail a certain illustrative embodiment of the invention, this embodiment being indicative of but one of the various ways in which the principles of the invention may be employed.